ESS 265

Chapter 11.

Raymond J. Walker

March 17, 1999

ESS265
Distributed Data Management

What are the Planetary Data System (PDS) and the Planetary Plasma Interactions Node (PPI)?

How is data prepared?

-PDS documentation
-Peer review

How do you locate and access data?

-DITDOS
-CDROM
-WWW

What about Space Physics?

Why Bother?

Why bother with data management and archiving?

-Many of the data are irreplaceable.
-Having many scientists work with the data leads to innovation and maximizes science return.
-It is the law.

Why bother with a distributed system?

-The best data products reside with people who use them to do their science.
-No university or laboratory has the expertise necessary to understand all of the data from all of the instruments
involved in planetary science.

The PDS Charge

Provide the scientific community with the highest quality planetary data forever!

Who is PDS?

PDS is a distributed data system managed by the Jet Propulsion Laboratory (JPL)

Planetary Plasma Physics

We have studied the interaction of the Earth's magnetosphere with the solar wind for over 40 years.

Mercury, Jupiter, Saturn, Uranus and Neptune have a similar interaction- supersonic solar wind
interacts with a magnetic field to form a magnetospheric cavity.

At Venus and Titan (when outside Saturn's magnetosphere) interact with the flow to form an induced magnetospheric cavity.

The Moon has a remanent magnetic field.

Mars too has localized field concentrations.

The small size and large amount of gas that evaporates from a comet make its interaction with the solar wind unique.

Asteroids may have a strong interaction with the solar wind.

Ganymede has an intrinsic magnetic field and small magnetosphere within the vast jovian magnetosphere.

Io is embedded in a sub-Alfvenic flow and the plasma impinging on Io is of Ionian origin.

Europa and Callisto have induced magnetospheres possibly related to a subsurface ocean.

Other planetary moons interact with plasma displaying a broad range of interaction parameters.

A new scientific discipline concerned with the physics of magnetospheres and ionospheres.

-Interaction between the solar wind and planetary obstacles.
-Processes which occur within the induced or intrinsic magnetospheres.
-Studies of the flow of energy and mass through these systems.
-Interaction of planetary wind with satellites.

Planets are closely coupled systems.

-Planetary atmospheres evolve due to plasma processes.
-Surfaces are bombarded by energetic particles and flowing plasma.
-Interiors of planets can be probed with low frequency magnetic variations.

The PPI Node

Number and variety of planetary plasma data sets is large.

Data for a given study often come from several instruments on a spacecraft in addition to Earth based observations.

-Distribute CDROMs to scientists who are willing to check the data and its usefulness.
-Make the CDROMs available through the PPI Node on-line system.
-Resolve any discrepancies in the data or documentation.

Sample PDS Label

Peer Review Process

-Documentation is reviewed for completeness and correctness.
-Data are reviewed for correctness.
-Data file descriptions are reviewed for adherence to standards.

Data are made available to the scientific community as soon as electronic versions are received by PPI.

-Data are listed as "under review" until they have completed the review process.
-Users are encouraged to report errors or deficiencies in the data or documentation back to the PPI Node as part
of the review process.

PPI Node-Data Management Considerations

can be used by an individual scientist to access data on a single CDROM.

Must adhere to PDS standards.

Minimize amount of effort to generate a "product".

Every product is completely self-contained.

-All necessary documentation and inventory information required to use the science data.
-Larger systems are built by using products as building blocks.

On-line information system for the PPI Node is an inventory and access system for every product offered by the PPI Node.

PPI Node- Inventory Tracking

Requirements

-Track the data regardless of its physical location.
-Track the data through modifications or revisions.
-Indicate associations between various data.
-Allow users to select pieces of databases and reassemble them into new databases.

Solution

-Distributed Inventory Tracking and Data Ordering Specifications (DITDOS).
-Tools to assist in the assembly of metadata and data in a networked environment.
-Servers for delivering metadata and data.
-Clients to access the server.
-Report generation tools.

-Stand-alone applications for individual users.

DITDOS

1. Three types of inventories.

-"Database" describes collections of products (Galileo data at Jupiter, Voyager 2 data at Neptune).
-"Product" is a collection of datasets which are contained on a single deliverable medium (CD-ROM).
-"Datasets" describes collections of physical data holdings.

Agents for Flatfiles

Preparing, Accessing and Using the Data

Generating DITDOS inventories

-Organize product by following PDS standards for volume design.
-Inventory building tool scans the volume and uses the PDS labels, the data and the location of the data on the volume to populate the inventories.